Ultrasound guidance in regional anesthesia: state of the art review through challenging clinical scenarios

Evaluating the impact of ultrasound-guided subsheath versus extrasheath sciatic nerve block on postoperative wound pain in tibial and foot surgeries: A systematic review and meta-analysis

This systematic review and meta-analysis evaluate the impact of ultrasound-guided subsheath versus extrasheath sciatic nerve blocks on postoperative wound pain in tibial and foot surgeries, crucial for effective pain management and patient recovery. Adhering to PRISMA guidelines, this study used a PICO framework, focusing on patients undergoing tibial and foot surgeries and comparing the efficacy and safety of subsheath and extrasheath sciatic nerve blocks. The literature search spanned four databases without time restrictions, assessing various outcomes like success rate, onset time, duration of analgesia and complication rates. Quality assessment employed the Cochrane Collaboration's risk of bias tool, and statistical analyses included heterogeneity assessment, fixed-effect and random-effects models, sensitivity analysis and publication bias evaluation using funnel plots and Egger's linear regression test. From an initial pool of 1213 articles, six met the inclusion criteria. The subsheath group showed a significantly higher success rate of complete sensory blockade within 30 min compared with the extrasheath group (OR = 5.39; 95% CI: 2.82-10.28; p < 0.01). No significant differences were found in procedure duration or incidence of nerve-related complications between the two techniques. The subsheath approach also demonstrated a quicker onset time of sensory blockade (MD = -8.57; 95% CI: -11.27 to -5.88; p < 0.01). Sensitivity analysis confirmed the stability of the results, and no significant publication bias was detected. Ultrasound-guided subsheath sciatic nerve blocks are more effective than extrasheath blocks in achieving rapid and complete sensory blockade for tibial and foot surgeries, with a quicker onset time and comparable safety profile. Subsheath injections are thus recommended as a preferred method for anaesthesia and postoperative pain management in these surgical procedures, enhancing overall patient outcomes.

Laser-Generated Leaky Acoustic Wave Imaging for Interventional Guidewire Guidance

Ultrasound (US) is widely used to visualize both tissue and the positions of surgical instruments in real time during surgery. Previously we proposed a new method to exploit US imaging and laser-generated leaky acoustic waves (LAWs) for needle visualization. Although successful, that method only detects the position of a needle tip, with the location of the entire needle deduced from knowing that the needle is straight. The purpose of the current study was to develop a beamforming-based method for the direct visualization of objects. The approach can be applied to objects with arbitrary shapes, such as the guidewires that are commonly used in interventional guidance. With this method, illumination by a short laser pulse generates photoacoustic waves at the top of the guidewire that propagate down its metal surface. These waves then leak into the surrounding tissue, which can be detected by a US array transducer. The time of flight consists of two parts: 1) the propagation time of the guided waves on the guidewire and 2) the propagation time of the US that leaks into the tissue. In principle, an image of the guidewire can be formed based on array beamforming by taking the propagation time on the metal into consideration. Furthermore, we introduced directional filtering and a matched filter to compress the dispersion signal associated with long propagation times. The results showed that guidewires could be detected at depths of at least 70 mm. The maximum detectable angle was 56.3°. LAW imaging with a 1268-mm-long guidewire was also demonstrated. The proposed method has considerable potential in new clinical applications.

Ultrasound-guided psoas compartment and sciatic nerve blocks for pain management of hind limb procedures in the alpaca (Vicugna pacos)

Background:

Loco-regional anesthetic techniques are considered important in the multimodal approach to analgesia in both human and veterinary medicine. No such techniques are described in the alpaca, bar the use of epidural. This is in part due to the lack of anatomical description for this species. While this limitation exists, the use of ultrasound guidance makes peripheral nerve blocks a viable possibility in the alpaca.

Case description:

A 12-month-old alpaca was referred for the treatment of a septic left tarso-crural joint. Due to a poor prognosis, amputation of the limb under general anesthesia was performed. Sciatic and psoas compartment blocks were attempted with the ultrasound-guided injection of ropivacaine prior to the start of the procedure. While the femoral nerve was possible to visualize, no obturator nerve was identified. A 5-year old alpaca was also referred for a left hind lateral claw removal, due to a squamous cell carcinoma. The sciatic nerve block was performed prior to the claw amputation under general anesthesia. No changes in heart and respiratory rate, or blood pressure suggestive of nociception, were observed in either of these cases. At the end of both the procedures, the patients experienced uneventful recoveries characterized by the ability to maintain the standing position, interest in food, and normal behavior.

Conclusion:

This report identifies the ease of performance and the challenges encountered using the ultrasound-guided psoas compartment and sciatic nerve blocks in the alpaca. It is our hope that this report encourages the use of ultrasound-guided loco-regional techniques in this species.

Role of dexmedetomidine as adjuvant in postoperative sciatic popliteal and adductor canal analgesia in trauma patients: a randomized controlled trial

Background

The effect of dexmedetomidine as an adjuvant in the adductor canal block (ACB) and sciatic popliteal block (SPB) on the postoperative tramadol-sparing effect following spinal anesthesia has not been evaluated.

Methods

In this randomized, placebo-controlled study, ninety patients undergoing below knee trauma surgery were randomized to either the control group, using ropivacaine in the ACB + SPB; the block Dex group, using dexmedetomidine + ropivacaine in the ACB + SPB; or the systemic Dex group, using ropivacaine in the ACB + SPB + intravenous dexmedetomidine. The primary outcome was a comparison of postoperative cumulative tramadol patient-controlled analgesia (PCA) consumption at 48 hours. Secondary outcomes included time to first PCA bolus, pain score, neurological assessment, sedation score, and adverse effects at 0, 5, 10, 15, and 60 minutes, as well as 4, 6, 12, 18, 24, 30, 36, 42, and 48 hours after the block.

Results

The mean ± standard deviation of cumulative tramadol consumption at 48 hours was 64.83 ± 51.17 mg in the control group and 41.33 ± 38.57 mg in the block Dex group (P = 0.008), using Mann–Whitney U-test. Time to first tramadol PCA bolus was earlier in the control group versus the block Dex group (P = 0.04). Other secondary outcomes were comparable.

Conclusions

Postoperative tramadol consumption was reduced at 48 hours in patients receiving perineural or systemic dexmedetomidine with ACB and SPB in below knee trauma surgery.

Technological Advances in Exotic Pet Anesthesia and Analgesia

Even when performed by skilled operators, locating the nerves can be challenging in small exotic pets; in such cases, the use of an electrical nerve stimulator may be useful to confirm the correct identification of the target nerve. Exotic animal anesthesia and analgesia have dramatically progressed over the past decade and continue to do so as more research and technologies develop. Technological advancements such as airway devices, endoscopic intubation techniques, positive intermittent pressure ventilators, and invasive and noninvasive blood pressure monitors have played a significant role in improving patient safety and the anesthetic outcomes of exotic animals.

Ultrasound-guided pulsed radiofrequency neuromodulation of the suprascapular nerve in partial rotator cuff tears

Background/Aim

Pulsed radiofrequency (PRF) of the suprascapular nerve has been shown to be effective in the treatment of chronic shoulder pain. Ultrasound (US) guidance has gained popularity in regional blocks recently. This study aims to investigate the efficacy of suprascapular nerve pulsed radiofrequency under the guidance of ultrasonography.

Materials and methods

This retrospective study included patients treated with PRF of the suprascapular nerve with a diagnosis of partial rotator cuff tears. The patients were assessed with a numeric rating scale (NRS), the Shoulder Pain and Disability Index (SPADI), and a Likert patient satisfaction score before the treatment and 3 weeks and 6 months following the treatment.

Results

A total of 31 patients was included in the study. The patients’ mean age was 66.8 ± 13.3 years. The mean scores of the NRS, SPADI, and Likert scale before the procedure (7.32 ± 1.1, 69.0 ± 8.5, 1.6 ± 0.6) and at 3 weeks (2.9 ± 2.1, 32.1 ± 17.20, 4 ± 1.2) and 6 months (3.2 ± 2.6, 33.9 ± 20.8, 3.8 ± 1.2) after the procedure were evaluated. We observed significant improvement in NRS, SPADI, and Likert scores at 3 weeks and 6 months following the treatment (P < 0.001).

Conclusion

The study demonstrated that US-guided suprascapular nerve PRF achieves good pain relief and functional improvement in patients with partial rotator cuff tears for at least 6 months.

A laser mount probe holder facilitates fixation of the optimized ultrasound image and needle alignment in-plane to the ultrasound beam during ultrasound-guided peripheral nerve block

Laser guidance facilitates needle alignment in-plane to the ultrasound beam. Once the ultrasound image is optimized, there is no further need to maneuver the probe. Therefore, we designed a laser mount probe holder prototype, and examined the ease of visualization of the needle tip using the laser mount probe holder. The needle brightness was quantitatively measured using an image analysis software. We found that the laser mount probe holder is useful, not only to visualize the needle tip in the ultrasound plane, but also to fix the best ultrasound image.

Laser Generated Leaky Acoustic Waves for Needle Visualization

Ultrasound (US)-guided needle operation is usually used to visualize both tissue and needle position such as tissue biopsy and localized drug delivery. However, the transducer-needle orientation is limited due to reflection of the acoustic waves. We proposed a leaky acoustic wave method to visualize the needle position and orientation. Laser pulses are emitted on top of the needle to generate acoustic waves; then, these acoustic waves propagate along the needle surface. Leaky wave signals are detected by the US array transducer. The needle position can be calculated by phase velocities of two different wave modes and their corresponding emission angles. In our experiments, a series of needles was inserted into a tissue mimicking phantom and porcine tissue to evaluate the accuracy of the proposed method. The results show that the detection depth is up to 51 mm and the insertion angle is up to 40° with needles of different diameters. It is demonstrated that the proposed approach outperforms the conventional B-mode US-guided needle operation in terms of the detection range while achieving similar accuracy. The proposed method reveals the potentials for further clinical applications.

Use of the cumulative sum method (CUSUM) to assess the learning curves of ultrasound-guided continuous femoral nerve block

BACKGROUND

Although ultrasound is a basic competence for anaesthesia residents (AR) there is few data available on the learning process. This prospective observational study aims to assess the learning process of ultrasound-guided continuous femoral nerve block and to determine the number of procedures that a resident would need to perform in order to reach proficiency using the cumulative sum (CUSUM) method.

METHODS

We recruited 19 AR without previous experience. Learning curves were constructed using the CUSUM method for ultrasound-guided continuous femoral nerve block considering 2 success criteria: a decrease of pain score>2 in a [0-10] scale after 15minutes, and time required to perform it.

RESULTS

We analyse data from 17 AR for a total of 237 ultrasound-guided continuous femoral nerve blocks. 8/17 AR became proficient for pain relief, however all the AR who did more than 12 blocks (8/8) became proficient. As for time of performance 5/17 of AR achieved the objective of 12minutes, however all the AR who did more than 20 blocks (4/4) achieved it.

CONCLUSIONS

The number of procedures needed to achieve proficiency seems to be 12, however it takes more procedures to reduce performance time. The CUSUM methodology could be useful in training programs to allow early interventions in case of repeated failures, and develop competence-based curriculum.

Evaluation of the knowledge base of French intensivists and anaesthesiologists as concerns the interpretation of respiratory arterial pulse pressure variation

OBJECTIVE

The aims of the study were to assess the knowledge of intensivists and/or anaesthesiologists concerning respiratory arterial pulse pressure variation (PPV) and to define the criteria used to indicate a fluid challenge.

STUDY DESIGN

A prospective observational study.

PATIENTS AND METHODS

Intensivists and anaesthesiologists from one region of France were evaluated for their knowledge about the prerequisites (continuous arterial pressure monitoring, regular sinus rhythm, mechanical ventilation without spontaneous breathing) and confounding factors shifting the threshold value of PPV (low tidal volume, decreased pulmonary compliance, low heart rate/respiratory rate ratio, right ventricular dysfunction, and/or intra-abdominal hypertension) using clinical vignettes. Criteria used by physicians to indicate a fluid challenge were also collected.

RESULTS

One hundred and forty-five physicians were included in the study. Among them, 87 (60%) knew prerequisites but none of them had full knowledge of all confounding factors. Criteria used to perform a fluid challenge were mainly PPV and the passive leg-raising test for the residents and PPV, blood pressure, oliguria and hydric balance for the qualified physicians.

CONCLUSIONS

PPV was widely employed to indicate a fluid challenge and 60% of the physicians knew the prerequisites. However, the physicians did not correctly interpret all confounding factors.

Anatomic variation of subclavian artery visualized on ultrasound-guided supraclavicular brachial plexus block

Use of ultrasonography for performance of nerve and plexus blocks has made the process simpler and safer. However, at times, variant anatomy of the visualized structures can lead to failure of blocks or complications such as intravascular injections. This is especially true in case of novice operators. We report a case of a variant branch of subclavian artery, possibly the dorsal scapular artery passing through the brachial plexus nerve bundles in the supraclavicular area. Since this variation in anatomy was visualized in the scout scan prior to the performance of the block, it was possible to avoid any accidental puncture. Hence, a thorough knowledge of the ultrasound anatomy is important in order to identify various aberrations and variations. It is also prudent to perform a preliminary scan, prior to performance of the block to localize the target area and avoid any inadvertent complications.